Modern vehicles and wind turbines often contain structures fabricated from composite materials, such as, for example, carbon fiber composites. In use, such composite materials undergo tensile strain due to environmental factors such as: extreme wind-speeds, air-resistance, and in-flight vibration.
Using traditional methods, curing composite structures is costly and typically requires a significant amount of time and energy to provide the required heat for curing. A common curing process uses an autoclave, which typically applies a combination of high temperature and pressure to heat a desired composite structure. In an autoclave, the temperature within the chamber must first increase prior to the composite structure. The composite structure is then heated from the outer surfaces, and sufficient time must be allowed to ensure that the inner core reaches similar temperatures. Typically, curing large structures such as wing skins and wind turbine blades requires very large autoclaves. However, these conditions make it extremely expensive to cure such large structures, where investment in specialized equipment or transportation is needed to secure autoclaves (or ovens, in some cases, as discussed below) of sufficient size. As a result, a wide variety of problems arise including increased manufacturing costs due to the significant amount of time and energy required to heat an autoclave, and size restrictions on composite structures desired to be cured imposed by the dimensions of an autoclave chamber.
In an effort to save time and costs, the aerospace industry has moved toward out-of-autoclave (OOA) materials, which only require atmospheric pressure via a vacuum to cure. However, ovens are still used to provide heat during the curing process of OOA materials. While OOA materials provide advantages over using autoclaves, the ovens used to cure them still suffer from the above deficiencies. For example, like autoclaves, ovens cure composite structures by heating an intermediate material inside a size-restrictive chamber. Another drawback of traditional ovens and autoclaves is that preheating an autoclave or oven to the curing temperature requires a significant amount of time and energy, which reduces throughput while increasing manufacturing costs.
Thus, what is needed is an economical curing system capable of heating a composite structure without requiring the aforementioned autoclaves and ovens, without sacrificing quality, or strength, of the composite structure. Curing of these composite structures internally during manufacture may significantly reduce cost, improve strength, and remove size limitations of cured composites.